What causes microphallus?

Updated: Nov 30, 2020
  • Author: Karen S Vogt, MD; Chief Editor: Sasigarn A Bowden, MD  more...
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Micropenis most often results from fetal testosterone deficiency. Testosterone deficiency may be caused by a defect anywhere along the hypothalamic-pituitary-gonadal axis or a defect in peripheral androgen action (5-alpha reductase deficiency or PAIS). Micropenis may also be caused by isolated growth hormone deficiency. It can occur as a primary idiopathic structural anomaly or may be associated with a genetic syndrome. The most common cause of micropenis is abnormal hypothalamic or pituitary function that leads to hypogonadotropic hypogonadism. The next most common cause is a primary testicular disorder that leads to hypergonadotropic hypogonadism.

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